Numerous examples of bicomponent fibers, particularly bicomponent polyolefin and bicomponent polyester fibers, and the processes for preparing them are known in the art. See, for example, The Encyclopedia of Polymer Science and Engineering, 3r ed., Vol. 11, pp 433ff.
Aranaga et al, Japanese Kokai Heisei 11-158733 discloses a bicomponent fiber of polyethylene terephthalate/polypropylene terephthalate (PET/PPT) having latent crimp. It is recognized in Aranaga and elsewhere that high recovery crimped fibers have potential for preparation of high value non-wovens.
Kakumoto et al, Japanese Kokai P2001-288620 discloses a process for preparing bicomponent fibers from two PET polymers differing in melt viscosity spun at speeds of 2,200 to 4,800 m/min then spun drawn in a separate stage and wound to produce a bicomponent fiber having latent crimp.
Tsuboi et al, Japanese Kokai P2002-61029 discloses a process for preparing a PET/PPT bicomponent fiber spun at 3000 m/min. The yarn so prepared is subject to a post-drawing step to realize crimp.
The art of spinning bicomponenet fibers is well-established. For example, U.S. Pat. No. 3,671,379 discloses the spinning of bicomponent polyester fibers, the equipment for accomplishing the spinning, and the design of the spinneret required to provide the desired product.